Abstract 5433: Knockdown of the glycolytic enzyme PFKFB2 induces growth inhibition and enhances paclitaxel sensitivity in ovarian cancer cells.

Abstract

Abstract Knockdown of certain glycolytic enzymes can affect ovarian cancer cell growth and enhance sensitivity to paclitaxel. 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-2 (PFKFB-2) is the cardiac isoform of the most important glycolytic regulator, phosphofructokinase-2, From the TCGA database of >300 ovarian cancers, the PFKFB2 gene ranked in the top 33% of overexpressed genes and in the top 19% of genes with copy number gain. We found that PFKFB2 mRNA was upregulated in 10 of 12 ovarian cancer cell lines when expression of the gene was compared to that in normal ovarian epithelial cells in culture. Knockdown of PFKFB2 with siRNA markedly inhibited cell proliferation and increased paclitaxel sensitivity in p53 wild type ovarian cancer cell lines as demonstrated in short-term cytotoxicity and long-term clonogenic assays. Liposome encapsulated PFKFB2 siRNA significantly inhibited growth (P<0.05) of human ovarian cancer xenografts in two ovarian cancer models (Hey A8 and A2780); even greater growth inhibition was observed when PFKFB2 siRNA treatment was combined with paclitaxel. Cell growth inhibition in cell culture was linked to G1 arrest and to a modest increase in apoptosis. Induction of p21Cip1 and p27Kip1 protein by PFKFB2 knockdown contributed to the G1 arrest, since silencing p21Cip1 and p27Kip1 dramatically reduced PFKFB2 knockdown-induced G1 arrest. PFKFB2 knockdown also modulated the expression of CDK2 and the phosphorylation of p27Kip1. Induction of p53 protein contributed to both PFKFB2 knockdown-induced G1 arrest and to apoptosis, since silencing p53 markedly alleviated PFKFB2 knockdown-induced G1 arrest and apoptosis. PFKFB2 knockdown inhibited expression of the ABC transporter family members ABCC4 and ABCG2 at the level of transcription, possibly contributing to enhanced paclitaxel retention and increased cytotoxicity after PFKFB2 knockdown. Taken together, these results suggest that PFKFB2 protein may regulate cell growth and sensitivity to paclitaxel by multiple mechanisms, particularly in p53 wild type ovarian cancers. As methods to deliver siRNA evolve in the clinic, PFKFB2 may provide a novel target for enhancing sensitivity to paclitaxel-based chemotherapy in patients with low grade serous ovarian cancer where p53 function remains intact. Citation Format: Shu Zhang, Weiqun Mao, Anil K. Sood, Nicholas B. Jennings, Cristian Rodriguez-Aguayo, Gabriel Lopez-Berestein, Zong-Fang Li, Robert C. Bast, Xiao-Feng Le. Knockdown of the glycolytic enzyme PFKFB2 induces growth inhibition and enhances paclitaxel sensitivity in ovarian cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5433. doi:10.1158/1538-7445.AM2013-5433